Refrigerating apparatus



Sept. 2, 1952 as. M cgQY 5 3 5 REFRIGERATING APRARATUS.

Filed A ril 21, 1950 mmmm I N SSE FIG?) 52 INVENTOR GRAHAM s. McCLOY (5.34.116. BY% 6 I? ATTORNEY Patented Sept. 2, 1952 UNITED STATES PATENT OFFICE REFRIGER-ATING APPARATUS Graham 5. Mc'Cloy, Springfield, Mass.,- assignor to Westinghouse Electric Corporation; East Pittsburgh, Pa., a corporation of- Pennsylvania Application April 21, 1950, Serial No. 157,252

'Th'i's"'invention relates to refrigerating apparatus and more especially to a means for rapidly defrosting such apparatus.

'It isan object "of this invention to provide a novelrefrigerating circuit which is also adapted to defrost the evaporator. p a

It is a further object of the invention to provide novel means for evaporating the refri erant liquid generated by the refrigerating apparatus when the evaporator is being defrosted.

These and other objects .are effected by my invention as will be apparentfrom the following description and claims'taken in connection with the accompanying drawings, forming a part of this application, in which:

' Fig. l is a schematic drawing of refrigerating apparatus and of the defrosting apparatus of this invention; f I

f 'Fig. 2 .is an enlarged view of the refrigerant liquid trap of the apparatus; and I Fig. 3 is a schematic drawing of 'a modification of the refrigerating and defro'stlng apparatus of H A V 7 Referring to the drawings, thereference nunieral lil designates a food storage chamber formed "by thermally insulated walls [2; An evaporator I4 is located in the upper portion of thechamber I and includes a refrigerant header it which communicates through'a metal suction tube l8 with the smaller end of a sealed metal casing 20. A portion [9 of the suction tube l8 passes upwardly through the insulated wall l2 of the chamber Ill. An electric motor 22, comprising a metal frame 23, a stator 24, and a rotor 25 is pressed into the smaller end of the sealed casing 20. @A compressor cylinder 28 is formed integrally with the frame '23 and contains a piston Bllwhich is actuated through 'a crank arm 32 'by'the rotor25. 4

The refrigerant passes through 'the air gap between the rotor 25and the stator 24 and through the opening 2'! infithefra'me- 23 and enters the compressor cylinder-28 through the inlet tube 29. The compressed refrigerant va-por passes from the compressor cylinder 28 through a tube "35 to a condenser 36 which condenses the refrigerant vapor to a liquid. The'refrigerant liquid is forced from'the 'eondensertfithrough a capillary impedance tube 38 'andthere'after passes through a somewhat larger metal tube 40 into a vessel i2 which forms a trap for the refrigerant liquid. The capillary tube 38 is in heat transfer relationship with a portion 41 of the suction conduit 18. The larger tube 40 is located in the insulated wall 12 of the chamber ll] adjusted the tube portion I9 of the suction tube I-8. An inverted U tube 44 communicates at one end 46 with a lower portion ofthe vessel 42 and at its other end 48 with the lower end of the evaporator ill. The supper portion of the U tube ll extends. above the liquid in the vessel 42' A small tube "50 connects an .3 'ClaimS. (Cl. 62 117.55)

2 i -i upper portion of the vessel with the adjacent portion of the inverted U tube M.

The electric motor 22 is' energized through leads 52 and 54- and a thermostatic switch 56' located in the lead 54.; The switch 56 is actuated A by a bellows 58 which communicates through a small tube 60 with a metal bulb 62 located in heat-transfer relationship with the evaporater M. The bulb 62 contains a small quantity of a volatile fluid so that the switch 53 is actuated in response to the vapor pressure-of this {fluid which in turn is responsive to the temperature of the evaporator It. The thermostatic switch 53 thus controls the operation of the electric motor 22 so that sufficientrefrigerant liquidis pumped to the evaporator Hi to maintain its ternperature substantially constant.

An electric heater 64 is located adiace-nt the tubes 40 and 19 and a second heater 68 adjacent a portion 68 of the suction tube ['8 lying near to the sealed casing 20, The heaters 64 and 65 are connected in parallel through leads l0; l2, l4 and a portion of the lead .54. A lead 16 and a manually operated switch 18 connects the lead H1 with the power Ilead v5.". to energize the heaters 64 and .66 when both the thermostatic. switch -55 and the manuallylcontrolled switch 1.8 are closed.

Operation The operation, in some respects, is the same asdescribed in Patent No. 2,459,173 and issued to the inventor of the present invention.

During the normal refrigerating operation of the apparatus, the switch 18 is open; When the temperature of the evaporator 14 rises to above a predetermined point, the thermostatic switch '56 closes, and theelectric motor 22 is ener'g i'zed to supply refrigerant liquid to l' he vessel '42. -The refrigerant liquid and the flash vapor passes through the small tube-50 into'the evaporator I' l wherein the liquid vaporizesand absorbs heat. The refrigerant liquid does, not flow through the elevated :portion of the tube '44 since the difference in pressure across the tube 53 ordinarily is not su'fiiciently great to force the "refrigerant liquid through the elevated portion of-the tube 4d against the force of gravity.

When the frost on the evaporator 1'4 has .ac cumulated to the point where defrosting is desired, the manually operated switchile is closed. If switch 56 is closed, or if open, when it closes, the heaters Bil and. Bliwill be energized and-the cle'ctric'motor2i2 will be in operation; Thehea-ter 54 vaporizes a sufficientquantity "of the 'refriger= ant liquid inthe tube li'l so that the difference in pressure across the tube '51] "becomes suilicientiy great to force the refrigerant liquid from the vessel '42 through .theelevated portion of the U tube 44 andinto the evaporator it; This floods the evaporator M and the header lt-withrefrigerant liquid and also partially hoods the suction tube "[8.

A portion of this refrigerant liquid is vaporized by the heater 64 when the refrigerant liquid passes through the portion 19 of the suction tube l8. Another portion of the refrigerant liquid in the suction tube I8 is vaporized by the warm refrigerant liquid in the capillary tube 38. A further portion of the refrigerant liquid is vaporized in the portion 68 of the suction tube by the heater 66 and the remainder will be vaporized after it enters the casing 20 by the heat of the electric motor 22 and the heat of the compressor 28, 30.

This vaporization of the refrigerant liquid in the tube l8 and in the sealed casing 20 raises the suction pressure in the evaporator l4 so that no vaporization and hence no cooling will take place therein. The cool refrigerant liquid in the header Hi, the evaporator 14, and in the vessel 42 will be replaced by the warm refrigerant being supplied by the capillary tube 38 and the tube 40 so that the temperature of the evaporator 14 is raised to above the freezing point and the frost on the evaporator melts. The heat of the heater 64 accelerates the defrosting of the evaporator l4 but is not essential if other means are employed to empty the vessel 42.

When the frost hasmelted, the manually operated switch 18 may be opened. This deenergizes the heaters 64 and 66 so that less refrigerant vapor is supplied to the vessel 42. The pressure difference across the tube 50 then decreases and the vessel 42 again fills up with refrigerant liquid to the level of the tube 50. Thereafter, the normal refrigerating action of the evaporator 14 will take place.

Modification A modification of the defrosting apparatus is shown in Fig. 3 of the drawings. In this modification, like parts are provided with the same reference numerals respectively. In this modification, the heater 68 is eliminated and the heat of the motor 22 is used more effectively to vaporize the refrigerant liquid in the suction tube l8. To this effect, a portion 82 of the suction tube I8 is coiled in intimate heat-exchange relationship with the small end of the sealed casing 20.

During the defrosting. operation, the compressor 28, due to the high suction pressure is heavily loaded so that it together with the driving motor 22, 24 tends to become quite warm. This heat is transmitted through the frame 23, the casing 20 and the portion 82 of the suction tube to the refrigerant liquid in this portion 82. The remaining refrigerant liquid which enters the sealed'casing cools the motor 22 directly and the cylinder 28 through the frame 23.

While I have shown my invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

What I claim is:

1. In mechanical refrigerating apparatus, the combination of a refrigerant compressor, a condenser for liquefying the refrigerant vapor compressed by said compressor, a refrigerant liquid trap for receiving refrigerant liquid from said condenser, a refrigerant evaporator, a first conduit connecting a lower portion of said trap with said evaporator, said first conduit having an elevated portion positioned above the liquid in said trap, a second conduit connecting an upper portion of said trap with said evaporator, said second conduit lying below the elevated portion of said first conduit, said second conduit including a restriction, a suction conduit connecting said evaporator with the inlet of said compressor, and heating means for increasing the vapor content of said trap to such a degree that the vapor passing through said second conduit causes such a difference in pressure to exist between said trap and said evaporator when the compressor is running that sufiicient refrigerant liquid is forced from said trap through said first conduit into said evaporator to flood said evaporator and to cause refrigerant liquid to flow into said suction conduit, said heating means being also in heat transfer relationship with a portion of said suction to vaporize at least some of the refrigerant liquid flowing in said suction conduit. I I

2. In apparatus for selectively refrigerating or heating an evaporator, a refrigerant circuit comprising a compressor, a condenser for liquifying the refrigerant vapor compressed by said compressor, a vessel for selectively storing or releasing liquid refrigerant, a liquid line including a restrictor for conveying refrigerant from said condenser to said vessel, conduit means connecting a lower portion of said vessel with said evaporator, said conduit means having an elevated portion positioned above the liquid in said vessel, said conduit means also having a portion thereof between said .ele'vated portion and said evaporator communicating with an upper portion of said vessel by means of a restrictor, and a suction conduit connecting said evaporator with the inlet of. said compressor, said suction conduit having a portion thereof 'in'eheat exchange relationship with a portion of said liquid line adjacent said vessel, and means for applying heat to the refrigerant flowing, in said circuit to effect defrosting of said evaporator, said means comprising a heating element disposed adjacent the heat exchanging-portions of said liquid line and said suction ,conduit to vaporize at least a portion' of the refrigerant flowing through said liquid line and said suction conduit. e

3. In refrigerating apparatus, the combination of a refrigerant circuit comprising, a compressor, a condenser forliquifying the refrigerant vapor compressed by said compressor, an evaporator, a liquid line including a restrictor for conveying refrigerant liquid from said condenser to said evaporator, and a suction conduit connecting said evaporator with said compressor, said suction conduit having a portion thereof in heat exchange relationship with a portion of said liquid line adjacent 'said evaporator, and means for applying heat tothe refrigerant flowing in said circuit to effect defrosting of said evaporator, said means comprising a heating element disposed adjacent the heat exchanging portions of said liquid line and said suction conduit 'to vaporize at least a portionv of the refrigerant flowing through said liquid line and said suction conduit. Y

GRAHAM S. McCLOY.

REFERENCES CITED The following references are of record in the file of this patent: 

